Atrial fibrillation is a disorder found in about 2.2 million Americans. During atrial fibrillation, the heart's two small upper chambers (the atria) quiver instead of beating effectively. Blood is not pumped completely out of them, so it may pool and clot. If a piece of a blood clot in the atria leaves the heart and becomes lodged in an artery in the brain, a stroke results. About 15 percent of strokes occur in people with atrial fibrillation. The likelihood of developing atrial fibrillation increases with age. Three to five percent of people over 65 have atrial fibrillation.
Several approaches are used to treat and prevent abnormal beating. Medications are used to slow down rapid heart rate associated with AF. These treatments may include drugs such as digoxin, beta blockers (e.g. atenolol, metoprolol, propranolol), amiodarone, disopyramide, calcium antagonists (e.g. verapamil, diltiazam), sotalol, flecamide, procainamide, quinidine, propafenone, etc. Electrical cardioversion may be used to restore normal heart rhythm with an electric shock, when medication does not improve symptoms. Drugs (such as ibutilide) can sometimes restore the heart's normal rhythm. These drugs are given under medical supervision, and are delivered through an IV tube into a vein, usually in the patient's arm. Radiofrequency ablation may be effective in some patients when medications don't work. In this procedure, thin and flexible tubes are introduced through a blood vessel and directed to the heart muscle. Then a burst of radiofrequency energy is delivered to destroy tissue that triggers abnormal electrical signals or to block abnormal electrical pathways. Surgery can be used to disrupt electrical pathways that generate AF. Atrial pacemakers can be implanted under the skin to regulate the heart rhythm.
In recent years, the pulmonary veins (PVs) and posterior left atrium (PLA) have been shown to play a role in the genesis as well as maintenance of AF. Despite an improved understanding of the underlying mechanisms of AF, current pharmacologic as well as ablative approaches to cure this arrhythmia are inadequate.